According to Deagol's website (info from A Descriptive Bibliography, p. 386), the magazine Show Vol.1 No.1. January 1970 includes excerpts from an interview with Tolkien (in Philip Norman's article "Lord of the Flicks").

Trying to find a copy for sale of this publication, I discovered this listing on Amazon.com. Being cautious I asked a seller if Norman's article was included but got a negative answer. Am I just looking at a similarly entitled magazine?

At Headington, near Oxford United soccer ground, Tolkien has a study in his garage. Dark-topped tobacco tins are left like markers along his shelves; and there is a good view of the rockets if some college beanfest explodes them. "I run to the window," Tolkien confesses, "every time I hear a whoosh."

I still think this might be the right magazine. I have a photocopy of the interview from pg. 29 in Show (I requested a copy from ILL when I was writing my M.A. thesis) and the interview is simply titled "FROM LONDON" in large bold font with "Lord of the Flicks" in very small font. No author is stated. I imagine the seller simply didn't notice this.

I will be purchasing one of those copies of Show on Amazon (as I think it is worth a gamble), but I'll wait to allow you to have first choice as you found this.